How Dog Tail Size Impacts Dog Communication

We all know non-verbal communication is key in how dogs communicate their feelings and general state of mind. We can observe whether a dog is relaxed, fearful, happy, submissive, dominant, and more by it’s overall body position, and movements of the head, ears, mouth, and by changes in the height and motion of the tail. And so can other dogs – surely much better than we can!

Considering a dog’s tail is important for interspecies communication, what are the implications for dogs with docked tails? Are these dogs (and perhaps those with naturally short tails) at a disadvantage when communicating with other dogs? In a recent post on dogbehaviorblog.com (a Woof Report favorite), Con Slobodchikoff, Ph.D., animal behaviorist and conservation scientist, and part of the team behind the blog, discusses a study from Leaver and Reimchen, which seeks to answer these very questions.

Dogs’ tails: in communication, size and motion matter

In the study, “Behavioural responses of Canis familiaris to different tail lengths of a remotely-controlled life-sized dog replica,” published in the journal Behaviourin 2008, Leaver and Reimchen used a life-sized remotely controlled dog model to examine the effects of tail docking on intraspecies communication in domestic dogs.

To conduct the study, the researchers employed a life-sized dog model, similar in appearance to a Labrador Retriever, and composed of a black synthetic fur-like material covering a wire frame and cotton-stuffed body. Its short (9 cm or 3.5 inches) or long (30 cm or 12 inches) tail was remotely controlled to display four possible conditions: short/still, short/wagging, long/still and long/wagging. Researchers videotaped interactions of 492 off-leash dogs in an outdoor dog park, looking at whether dogs freely approached the model or hesitated before doing so, and also divided the dogs into two categories, large and small.

The use of a dog model was an interesting addition and enabled researchers to test just for the changes in tail movement and size, which would be impossible to test in ‘real world’ conditions. The researchers explain not only would it be difficult to find dogs of the same breed with and without docked tails, but that other factors would also influence the study, such as the individual behaviors of the dogs and additional body language cues.

A summary of the findings:

Researchers predicted the difference in response to the dog model would simply vary with model taillength, with dogs approaching a short tail more cautiously due to the lack of social cues. However, researchers more frequently observed differences in response to tail length when tail motion was involved.

Larger and smaller dogs were more likely to approach the long/wagging tail compared to the long/still tail.

Larger and smaller dogs did not differentiate between the short/still and short/wagging tail, and approached the model at the same rate, which was a rate lower than the long/wagging tail and higher than the long/still tail.

Overall, the researchers provided evidence that “a longer tail is more effective at conveying different intraspecific cues, such as those provided by tail motion, than a shorter tail.” In addition, the researchers stated, “docking a dog’s tail may impair intraspecific communication.”